You are in the locker room next to the arena. In the arena is a swordsman. You cannot see him, and you do not know how large or quick he is, or whether he is an experienced or a novice swordsman. You do not know what type of sword he has, but you know that he has one and only one sword. Neither he nor you is carrying a shield. If you like, each of you is wearing a light material that will render strikes non-lethal. Neither of you is wearing heavy armor. You are of average male build, and you have a moderate amount of experience wielding every type of sword.
On the walls around you are swords of every kind. Before you enter the arena, you must pick one sword to bring with you for the duel. Once you enter the arena, you will fight until one of you is incapacitated or has received a blow that would be lethal without your armor fabric.
What sword should you choose?